Premature hair loss or balding has numerous causes. The most common of these is androgenic alopecia, also called male or female pattern baldness. In this condition, the presence of extra hormones, testosterone and DHT, affect the growing cycle of hair, causing more than the usual shedding of hair and death of hair follicles. In at least 90% of cases, premature hair loss is due to androgenic alopecia.

Hair loss in women, particularly when they reach their late thirties or forties and begin to produce less estrogen, can be tied to this loss of estrogen. Women who have been pregnant may have experienced especially thick and lustrous hair during their pregnancy due to extra estrogen. When estrogen levels begin to decline, hair growth slows, and some follicles may die. Estrogen therapy can slow premature hair loss, but there are some downsides to using it. It is indicated in a much higher risk for certain cancers and hormone replacement therapy is now used with far less frequency.

Scientists also point to many medications that can result in premature hair loss. For instance, thyroid hormone can cause hair to shed, though lack of thyroid hormone can also create hair loss. Certainly medications like those used for chemotherapy cause temporary premature hair loss, which regrows after the treatment is stopped. Certain medications for mood disorders and seizures, like carbamazepine (Tegretol®), used often by people with bipolar disorder can result in premature hair loss, as can a number of antidepressants. Medications that list hair loss as a side effect do not necessarily mean that hair loss is assured or will be significant, merely that there is a potential for losing hair.

Malnutrition may affect hair growth and result in premature hair loss. When a person is severely malnourished, or a person has a condition like irritable bowel syndrome, the body either doesn’t have access to or can’t absorb necessary vitamins and minerals. When malnutrition is a factor, baldness can result even in very young children. Again, this hair loss doesn’t necessarily cause the death of hair follicles, and if adequate nutrition is achieved, premature hair loss can be temporary.

Another condition that can result in patchy baldness is trichotillomania, a disorder marked by a compulsive desire to pull out the hair. Trichotillomania is considered similar to obsessive-compulsive disorder and can respond to treatment with certain antidepressants and with cognitive behavioral therapy. While it continues, excessive pulling out of the hair can damage hair follicles to the point where they no longer function. It is best to treat this condition early when possible, to avoid such damage.